- Added `--blank` flag to generate project skeletons (no sample content)
- Removed unused import `dart:async` from tool/hop_runner.dart
- Added blank project's drone.io entries

Signed-off-by: Claudio d'Angelis <claudiodangelis@gmail.com>
Merge pull request #4 from claudiodangelis/master

Added `--blank` flag to generate project skeletons (no sample content)